588 



Female. — Color similar to that of the male. 



Head similar to that of the male. 



Thorax : black stripe of the mesopleural suture divided by a line 

 of brown ; mesostigmal plates as shown in Figure 224. 



Abdomen: terga 1-7, inclusive, similar to corresponding terga 

 of the male, the lateral blue stripes of the margin becoming dull 

 brown on the apical segments; eighth tergum black, with pale blue 

 lateral spots on the caudal margin; tergum nine blue, with two short 

 dorso-lateral black stripes which fuse at the base of the meson; 

 tergum ten blue; anal appendages dark brown, ovipositor pale buff, 

 the prostyles short and blunt. 



Measurements 



Length, $ 29-33 mm. 



Length, 9 32 mm. 



Length of abdomen, $ 24-28 mm. 



Length of abdomen, 5 26 mm. 



Length of hind wings, $ 17-18 mm. 



Length of hind wings, 2 18 mm. 



Width of hind wings, $ 3.5 mm. 



Width of hind wings, 5 3.5 mm. 



This species is very closely related to e.vsulaiis, the male differing 

 principally in the possession of blue on the eighth tergum and in the 

 character of the anal appendages. The female can not be separated 

 from, exsulans except by the mesostigmal plates. It is, however, a 

 much more slender and delicate insect. 



Described from eighteen males and one female in the collection of 

 Mr. E. B. Williamson. 



A rare species, reported from Ohio, but not yet taken in Illinois 

 by collectors. 



Enau.agma doubledayi Selys 



Nymph. — Unknown. 



Adult; Male. — Color, light blue and black. 



Head blue and yellowish and black; antennae uniform brown, 

 the second segment slightly longer than the first ; anteclypeus and 

 labrum shining yellow; exposed portions of the mandibles, their 

 trochantins, genae, and the front dorsad of the clypeus to the level of 

 the antennal fossae pale ; remainder of the front black ; postocular spots 

 small, the narrow stripe caudad of the ocelli distinct; occiput and post- 

 genae pale ; compound eyes dark brown. 



